FoxM1mRNA癌相关选择性剪接的机制研究

FoxM1 is a transcriptional factor and plays an important role on oncogenesis and caner progress. FoxM1 contains three isoforms namely FoxM1A，FoxM1B and FoxM1C. FoxM1B and FoxM1C are overexpressed on cancer tissues and act as active transcriptional factors. However, FoxM1A is lower expressed on cancer tisssues and functioned as an inactive transcriptional factor. Thus，the prior selection for isoforms FoxM1B/C in cancer tissues is helpful for cancer genesis and cancer development, which is caused by cancer associated alternative splicing. So it is necessary to make clear the mechanism of cancer associated alternative splicing. On basis of characters of its splicing and our preliminary study, we deduce that the regulation of FoxM1 splicing in cancer is due to mutation of its cis-splicing regulatory elements and abberant expression of cancer associated trans-splicing proteins. In this project, we will constrct FoxM1 Minigene to evaluate its cis-splicing regulatory elements and identify its trans-splicnig proteins by peptide fingerprint ananlysis. We will further confirm the effects of splicing factors on FoxM1 by intro and in vivo experiments. Finally,we will analyze the mutation of FoxM1 cis-regulatory elements with gene MS and combine the expression pattern of FoxM1 isoforms and trans-splicing factors in ovarian cancer tissues to evaluate the correlation among them, identify relationship of cancer associated alternative splicing of foxm1 with the pathological grade, clinic stage and prognosis of ovarian cancer cases and provide clues for ovarian cancer therapy.

FoxM1是与癌发生、发展密切相关的重要的转录因子。它具有FoxM1A、B和C三种剪接异构体。FoxM1B和C在癌组织中高表达，发挥转录激活、促癌发生和发展的作用，而FoxM1A在癌组织中低表达，发挥转录抑制功能。癌组织中FoxM1B/C的优先选择对于FoxM1发挥促癌作用非常关键。因此对这一现象的成因即FoxM1癌相关选择性剪接机制的研究非常重要。根据其剪接特点和预实验结果，我们推测此剪接机制可能主要缘于顺式剪接调控元件的突变和癌相关反式剪接作用因子的异常表达。本课题利用FoxM1的Minigene等手段来确定其剪接状况，判断剪接顺式调控元件。利用肽指纹图谱技术确定其剪接作用因子，在体内外验证其作用。最后，我们利用基因质谱技术分析卵巢癌组织样本中剪接顺式元件的突变情况，结合FoxM1剪接异构体、剪接作用因子表达谱进行相关性分析，并进行临床病理分期、分级及预后分析，为卵巢癌治疗提供线索。

FoxM1是与癌发生、发展密切相关的重要的转录因子。它具有FoxM1A、B和C三种剪接异构体。FoxM1B和C在癌组织中高表达，发挥转录激活、促癌发生和发展的作用，而FoxM1A在癌组织中低表达，发挥转录抑制功能。癌组织中FoxM1B/C的优先选择对于FoxM1发挥促癌作用非常关键。本课题利用FoxM1的Minigene等手段来确定其剪接状况，鉴定出了其剪接顺式调控元件，并利用肽指纹图谱技术确定了其剪接作用因子SF。用siRNA将其干涉后，FoxM1B/C 显著下降，FoxM1A的表达显著上调，卵巢癌临床病理样本也表明FoxM1B/C 与其表达具有相关性（r=0.061）。功能实验表明FoxM1B参与乳腺癌对多西紫杉醇的耐药作用. 在卵巢癌组织中，FoxM1与卵巢癌的不良预后有关，促进了卵巢癌MMPs、VEGF的表达从而参与卵巢癌的转移过程，FoxM1也能够通过直接转录调控GLUT1和HK2调节卵巢癌细胞的糖代谢重编程。综上所述，本课题表明SF促进了FxoM1B/C剪接体的表达，FoxM1剪接体在乳腺癌及卵巢癌的进程中发挥了重要作用，有可能作为乳腺癌及卵巢癌之治疗的潜在靶点。